"""add is_last to delivery-taskRevision ID: 233cdabdfe51Revises: 56765d423498Create Date: 2013-05-22 14:31:46.727000"""# revision identifiers, used by Alembic.revision = '233cdabdfe51'down_revision = '56765d423498'from alembic import opimport sqlalchemy as sadef upgrade():    op.add_column("TB_DELIVERY_TASK", sa.Column("is_last", sa.Boolean, default=False, nullable=False))def downgrade():    op.drop_column("TB_DELIVERY_TASK", "is_last")